Mobile roof supporting shield

ABSTRACT

A flexible shield protecting excavating activities in a tunnel from roof falls is made mobile by its drivable underlying support structure. Double acting hydraulic jacks, which are retained upright by pivotal and flexible members in each section of a train of sections comprising the support structure, underpin the flexible shield, and are operable to alternately apply the flexible shield in close proximity to the tunnel roof and maintain it free from engagement with the roof to facilitate its displacement along the tunnel with the support structure. A webbing of interlaced straps which take shape within edge supporting cables form panels corresponding to the sections, and these panels are integrated by nonrigid connections at the jack structures to make a canopy arrangement constituting the flexible shield.

United States Patent [191 Barrett Sept. 2, 1975 I MOBILE ROOF SUPPORTINGSHIELD Primar Examiner-Dennis L. Ta lor 75 1 t: Ath L.B u,o1 t,V. y Y 1men or r ur arre ouces er a Attorney, Agenl, or Firm-Gersten Sadowsky;Donald [73] Assignee: The United States of America as R Fraserrepresented by the Secretary of the Interior, Washington, DC.

' [57] ABSTRACT [22] 'Filed: June 25, 1973 Appl. No.: 357,737

US. Cl 61/45; 61/63 Int. Cl. E2lD 15/44 Field of Search 61/45 D, 45 C,63; 299/11,

FOREIGN PATENTS OR APPLICATIONS 11/1971 Germany 6l/45 C A flexibleshield protecting excavating activities in a tunnel from roof falls ismade mobile by its drivable underlying support structure. Double actinghydraulic jacks, which are retained upright by pivotal and flexiblemembers in each section of a train of sections comprising the supportstructure, underpin the flexible shield, and are operable to alternatelyapply the flexible shield in close proximity to the tunnel roof andmaintain it free from engagement with the roof to facilitate itsdisplacement along the tunnel with the support structure. A webbing ofinterlaced straps which take shape within edge supporting cables formpanels corresponding to the sections, and these panels are integrated bynonrigid connections at the jack structures to make a canopy arrangementconstituting the flexible shield.

8 Claims, 8 Drawing Figures PATENTEU SEP 2 I975 SEIZE? MOBILE ROOFSUPPORTING SHIELD The invention relates to apparatus for protectingpersonnel and equipment from the hazards of roof falls in undergroundmining operations. More particularly, the invention is in an integratedmobile apparatus in which an elevated flexible shield is adapted tocatch the falls of dislodged portions of a mine roof before they reachthe subjacent men and machinery.

Protection from roof falls in mine tunnels had heretofore been soughtfrom mobile apparatus which provided roof support rather than shieldingfrom falling roof material. A desired mobility for such roof supportapparatus, which allows it to progressively move along with miningmachinery advancing the tunnel face, is often made difficult by therigid roof beams and vertical catenary beams normally used therein toengage the tunnel roof supported thereby. In addition, the great amountof space occupied by such apparatus, due largely to the bulk and size ofits support beams, makes them generally unsatisfactory in tunnelingoperations common to face mining of coal. Apparatus disclosed in US.Pat. No. 2,795,935, granted June 18, 1957, to C. W. Fitzgerald, and US.Pat. No. 2,795,936, granted June 18, 1957, to W. A. Blower et al, areexamples of mobile roof supports wherein rigid roof engaging members,such as l-beams, or structural members, are used. Mobility for thesepatented roof supports is gained by a combination of hydraulicallypowered, double-acting piston drives of uprightjacks and horizontal rammechanisms provided for individual units of a total apparatus. Each unitcomprises two pairs of the jacks of which the separate jacks of eachpair support a beam, extending traversely across the mine tunnel,through pivotal connections between upper piston ends of the jacks andthe beam near the extended ends thereof. Jacks of the respective pairsat corresponding ends of the beams are joined through rotatableconnections to the ram drive mechanisms which are selectively operableto retract or extend either jack with respect to the other.Consequently, each unit is individually displaceable in either directionalong the tunnel path by a walking sequence where after one pair ofjacksis operated to disengage its associated beam from the mine roof, rammechanisms are operated to drive this pair ofjacks and the beam thereonoutwardly from the other pair of jacks whose associated beam hadremained engaged with the tunnel roof. Subsequent rcengagement of thebeam of the one pair of jacks is followed by a disengagement from thetunnels roof of the beam of the other pair of jacks, and operation ofthe ram mecha nisms to draw the other pair of jacks and the beam thereoninwardly toward the one set ofjacksv Thereafter this other pair ofjacksis operated to reengage its associated beam with the tunnel roof. Eachunit of the apparatus following a previously moved unit is in turnwalked by means of the same sequence of operational control beingimparted to its pairs of jacks and rams. The less bulky flexible shieldarrangement according to at least one embodiment of the presentinvention is more easily moved along the path ofa mine tunnel with theuse of an arrangement of hydraulic jacks and ram mechanisms. However,the propulsion arrangement in this embodiment of the invention is anintegral part of the larger apparatus rather than a part of eachindividual unit of an apparatus. A further embodiment of the inventionhaving a caterpillar type propulsion mechanism for each of its unitsobtains a still greater maneuverability in a tunnel when such units arecooperatively interrelated with the flexible shield arrangement.

The invention herein features a flexible canopy adapted for applicationto the: differing segments of the mine tunnel roof encountered as thetunnel face is advanced by the mining activity over which this canopy ismaintained, and a support structure for the canopy which allows anextensive contact between the canopy and the mine roof in spite of theirregularities of the roof surface. Maintaining the: canopy as indicatedis a propulsion means which in effectuating movement of the canopythrough the mine tunnel is capable of displacing the canopy so as tovary it in width, as well as rectilinearly and angularly.'Clharacterizing this propulsion means are elongated front and back endsections,

each of which has operatively connected therewith, at inner endsthereof, a relatively shorter articulated driver section, and aselectively controlled power generating section operatively connectedbetween the inner ends of the respective driver sections. The severalsections are essentially quadrangular in form in that each section isdefined by upright extensible hydraulic jacks in four corners thereof.However, each of the driver sections takes its form from a pair of jacksat the inner end of the adjacent end section, and two jacks of the powersection adjacent thereto. Vertical stability for this sectionalarrangement is maintained by cross brace structures extending betweeneach pair of the upright jacks aligned in cross-sectional planes of thetunnel, and further bracing elements extending between each set of twojacks in the respective end sections which stand adjacent the same sidewall of the tunnel. Extensible, double-acting hydraulic ram devices arehorizontally disposed in the driver sections by flexible connections toadjacent jacksaligned with the side walls of the tunnel. Each side ofthe power section is provided with an elongated, narrow platform,maintained horizontally by pivotal connections to the power sectionjacks adjacent thereto, on which are affixed a hydraulic oil tank, pumpand motor, and a panel of controls for valves which determine theoperation of various jacks and ram drive devices of the apparatus. Eachjack has an upper linearly displaceable and rotatable piston part towhose outer extended end is pivoted a laterally extending, relativelyshort horizontal beam. Affixed to the upper surface of each of thesebeams, near the extended ends thereof, are short posts having superposedthereon roof engaging areas such as a knobbed pad or a pointed conicalhead. Suspended from this multiplicity of posts on the horizontal beamsare several panels of flexible webbing constituting the overhead canopyof the apparatus. The further embodiment of the invention has a yetsimpler construction wherein individual linearly displaceable androtatable jacks are mounted fore and aft to its caterpillar propulsionmechanism by means of flexible and pivotal connections. The flexiblecanopy construction, and the generally flexible mobile support structureprovided therefor in each embodiment, allow an apparatus according tothe present invention to have complete utility in tunnels of differingsizes and shapes.

It is therefore an object of the present invention to provide a mobileroof shield under which men and machines perform mining operationswithout hazard from falling roof material.

A further objective of the present invention is to provide a generallyflexible mobile shield against mine roof falls which is accommodative toa diversity of mine tunnel configurations.

These and other objects and advantages of the present invention willbecome more fully apparent from the following detailed description ofthe invention set forth herein and from the accompanying drawings made apart hereof in which:

FIG. 1 is a partially schematic side elevational view of the overallapparatus according to one embodiment of the present invention;

FIG. 2 is a plan view of a fragmentary showing of the apparatus as shownin FIG. 1;

FIG. 3 is an end view, taken along line 3-3 in FIG. 1, showing crossconnections between opposite sides of the apparatus;

FIG. 4 is a fragmentary showing, partly in section, of a spiked post inthe canopy supporting structure;

FIGS. 5 and 6 are fragmentary showings of the canopy and structuralsupport elements therefor; and

FIGS. 7 and 8 are partially schematic side and end elevational views offragmentary showings of a second embodiment of the present invention.

With reference to FIGS. 1 to 3, the apparatus according to the presentinvention is disclosed therein as serving to protect against roof fallsover a mining activity in a tunnel 8 being cut in substances such asstratums of coal. In use this apparatus maintains a protective shieldingin the form of a canopy 10 contiguous to tunnel roof 12 when theapparatus is held stationed between side walls 14 and 16 of the tunnel,by parts thereof placed securely in contact with the tunnels floor 16and its roof, following periodic displacements of the apparatus to keepup with the mining activity. The larger structural components of theapparatus may be viewed, for the purposes of the present explanation, asincluding in combination a front end section 20, a back end section 22,and a power generating and control section 24 interconnected to thefront and back end sections by a front driver section 26 and a backdriver section 28, respectively. Section is effectively an activatablerectilinear framework having as a superstructure thereon a flexiblepanel characterized by its mesh of relatively wide webbing. Comprisingthis framework are four double-acting hydraulic jacks, including jacks30, 32 and 34 visible in FIGS. 1 and 3, which effectively constitutecorner posts of the generally rectangular structure of section 20wherein these jacks are maintained upright by interconnections with acombination of rigid, extensible and flexible beams. Thus, on the sideof this structure adjacent tunnel wall 12, jacks and 32 obtain supportfrom a rigid horizontal beam 36 pivotally connected to heavy duty,relatively wide bands 38 and 40 affixed to the respective jacks adjacentto the lower parts thereof, and extensible horizontal beam 42 pivotallyconnected to corresponding bands 44 and 46 affixed to the respectivejacks adjacent to the upper parts thereof, and a rigid beam 48 disposeddiagonally between beams 36 and 42, in the plane thereof, by pivotalconnections to the respective outer cylindrical housings 50 and 52ofjacks 30 and 32. The further two jacks of section 20, includingjack34, on the side thereof adjacent tunnel wall 14, are also maintainedupright with the assistance ofa support therefor wherein upper and lowerhorizontal beams and a diagonal beam are interconnected with these jacksby pivotal connections which are the counterparts of those heretoforedescribed for the aforesaid one side of the section. The respectiveupper horizontal beams of the structures side supports are renderedextensible by relatively stiff spring coupling devices therein such asthat represented by device 54 in beam 42 whose pivotal connections tojacks 30 and 32 are made from the enclosure housing of device 54 and theextended end of a piston member coupled to the housing by the springenclosed therein.

Lateral support for the structure of section 20 is achieved withflexible composite members which extend between the jackscorrespondingly situated on the opposite sides of the structure. As mostclearly appears in FIG. 3, front end jack 32 and jack 34, its front endcounterpart adjacent side wall 14 of the tunnel, are tied together by acomposite cross beam 56. Comprising beam 56 are a centrally situated boxgirder 58, and elongated multiple leaf springs constituting flexiblemembers 60 and 62 which are combined with the girder to form an archedspan over the forward workin g area of section 20. More specifically,end portions of the respective leaf spring members have a set thereinwith respect to a long central portion thereof, which facilitates theattachments separately of such end portions within the respective endopenings in girder 58 and channel-like clamp devices 64 and 66 fitted tothe outer cylindrical housings of jacks 32 and 34, respectively. In thesame way jack 30 and the jack corresponding thereto on the opposite sideof the structure, are tied together by a composite cross beam comprisingsymmetrically arranged leaf spring members which by attachments to therespective jacks and a box girder form the structure extending betweenthe jacks which spans across the working area in the tunnel at the rearof section 20.

The four jacks constituting section 20, and the other upright jacks ofthe apparatus herein, are all conventional double acting hydraulicpowered prop structures of the type more fully described in thepreviously identified patent to Blower et al. Each such jack stands on afloor engaging foot or pad 68 thereof having a shallow convexity whichallows the jack to participate in a minor degree of roll on irregularsurfaces of tunnel floor 16. The floor pads are affixed beneathcylindrical outer shells of the jacks, such as housings and 52 of jacks30 and 32, respectively, which enclose a hydraulic cylinder wherein apiston is reciprocable for vertically displacing a piston rod. Thus,jacks 30, 32, and 34 are equipped with upright piston rods 70, 72, and74, respectively. Pivotally supported at the upper ends of piston rods70, 72, and 74, are relatively short, laterally extending, or crosschannel beams 76, 78, and 80, respectively. The pivotal connections aremade in an obvious manner by pivot pins, which are journaled in holesextending horizontally through upper end portions of the piston rods,engaging holes at mid-points in the opposite flanges of the channelbeams. Thejack laterally opposite to jack 30 in section 20, as well asthe other jacks of the further sections of the apparatus, each haveprovisions therein for a hydraulic cylinder in which a piston togetherwith the rod thereof are reciprocable. To each of the respective endportions of the further piston rods is pivotally mounted a laterallyextending channel or cross beam in the manner heretofore described forthe jacks of section 20. Accordingly, further jacks 82, 84, 86 and 88,which are visible in FIG. l, are equipped with piston rods 90, 92, 94and 96, respectively, on which are pivotally mounted channel or crossbeams 98, 100, 102 and 104, respectively.

Referring particularly to FIGS. 1,3 and 4, it will be seen that each ofcross beams 78'and 81) have affixed to their outer back surfaces, at ashort distance from each of the respective extended ends thereof, aspiked post. Cross beams 76, 98, 100, I02, and 104, which are visible inFIG. 1, and the croresponding cross beams laterally spaced'from each ofthose indicated such that they are adjacent tunnel wall 14, each alsohave similarly affixed thereto a spaced pair of spiked posts. Posts 110and 112 affixed to cross beam 78, and posts 114 and 116 affixed to crossbeam 80, as well as each of the posts affixed to the other cross beamsof the apparatus, have a configuration which more fully appears in theshowing of FIG. 4 where post 110 is seen as comprising a reducedcylindrical mid-section 118 surmounted by a conical spike 120. Referenceto FIGS. 2 and 4 to 6, show these spiked posts as constituting means formounting canopy upon the'respective sections of the apparatus. As washereinbefore indicated with respect to section of the apparatus,canopy10 is made up of individual panels of meshed webbing. Nylon strapsserve as webbing in the presently disclosed embodiment,although the useof other strap or sheet materials of adequate strength, such as metalstraps, would be satisfactory; Steel cables are used to support thewebbing along the four edges of each panel, and two additional steelcables are provided to lend support at intermediate points on the panel.Thus, an interlaced webbing of straps 130 forming a mesh constitutes theshielding of a panel 132 operative in section 20.

Maintaining the shape of panel 132 are its opposite end support cables134 and 136, and its opposite side support cables 138 and 140, havingtheir respective extremities attached to generally oval links which arefitted upon the several posts of the four channel beams including beams76, 78, 80, and the beam adjacent tun nel wall 14, laterally opposite tobeam 76. An additional supporting cable 142 tied to links fitted uponposts 144 and 112 of the facing cross beams 76 and 78, respectively, isinterlaced in the webbing of panel 132. Further support is provided by acable, not shown, which threads through panel 132 between attachmentsthereof to links fitted upon post 114 and the post opposite thereto onthe beam facing beam 80. Posts 144 and 146, which are affixed to crossbeam 76, appear in FIG. 5 as providing means for appropriately retaininga portion of end cable 134 in panel supporting position. It should beevident from the showing in FIGS. 4 and S that the attachment links areeasily fitted to their posts by lowering a wider end opening of the linkover the posts conical spike and down to the reduced midsection thereof,and thereafter shifting the link with respect to the post such that anarrower end opening of the link engages the posts mid-section whereatit is locked under a flanged portion of the spike. The posts mid-sectionis of sufficient height to thusly accommodate two links. Accordingly, alink 148, fitted to post 144, facilitates the attachment thereto ofsegments of cable 134 and cable 142, and a further link 150, fitted topost 146, facilitates the attachment thereto of an end segment of cable134 and side support cable 138. Attachments of the cables to the linksare made as shown, by way of example, in FIG. 6, where link 148 is seenas carrying a thimble sleeve 152about which is wrapped a length of cable134, and clip type clamps 154 and 156 are applied and secured in aconventional manner to bind together overlapping portions of the cable.The straps ofzmesh 130, such as strap 158 appearing in FIGS. 5 and 6,are appropriately overlapped and sewn at their extremities to providesuitable loops through which the cables are caused to extend in anobvious manner. Straps dependent from central portions of their supportcables are maintained suitably separated by spacer sleeves riding on thecables; as for example spacers 160 shown in FIG. 5. As'is indicated inthe showing of FIG. 5, the straps of panel 130 are of such length anddistribution thereon that the edges of the panel may assume a curvedcontour. These edges are so shaped to fit uniformly and in closeproximity to a complementary contour given to the edges of an adjacentpanel, to be hereinafter more fully described, when the several panelsare assembled to form canopy 10 as an integral shield. The: respectivecross beams, from which the panels are dependent, take requisite angularor skewed dispositions in the approximate plane of the canopy, allowedby the rotatability of the pistons in the supporting jacks, toaccommodate the curved forms of the supporting cables of thecomplementary shaped panels.

Sections 22 and 24 of the apparatus have operationally associatedtherewith further mesh panels and l72,'respectively, which in their formand structure are identical'to panel 132 previously disclosed forsection 20; As should be evident from the foregoing, the respectivesections 22 and 24 are each equipped with eight spiked posts havingfittedthereto the requisite oval links which facilitate the attachmentsof the cables giving form to panels 170 and 172. However, sections 26and 28 of the apparatus have operatively associatedtherewith-intermediate panels and 182, respectively,'which, as will beseen by reference to FIGS. 1 and 2, are substantially shorter than thepanels previously described, although they are coextensive in lengthwith those panels. Moreover, as was previously indicated, strapscomprising panels 180 and 182 are of such length and distributionthereon that the longer edges of the panels are contoured to matchadjacent complementary edges of the larger panels. Further, panels 180and 182 are equipped in the manner of the larger panels in that eachincludes a requisite number of oval links which faciliate the attachmentof panel forming cables. On the other hand, the links of panels 180 and182 share the spiked posts of the sections adjacent thereto. Morespecifically, the links of panel 180 are locked under the spikes ofposts in sections 20 and 24 where they are effectively maintained, asillustrated in FIG. 5 by exemplary links 184 and 186, on the postsaffixed to cross beams 76 and 98, and the corresponding cross beamslaterally spaced from these beams and adjacent to tunnel'wall 14. Linksof panel 182 are similarly effective when maintained on posts affixed tocross beams 100 and 102 on jacks 84 and 86, respectively, and crossbeams on jacks laterally spaced therefrom in sections 24 and 22.

Driver sections 26and 28 of the apparatus are each characterized bycontrollable arrangements therein having a cooperative interaction withthe jacks in the adjacent sections which are contiguous thereto. Thus,an arrangement at each side of a driver section includes a pair ofhorizontal extensible linkages articulately connected to the aforesaidcontiguous jacks at each side of the section. The linkages of each suchpair are respectively connected to upper and lower bands affixed to thejacks, as is exemplified by the illustration in FIG. 1 with respect toone side of section 26 where a lower linkage 190 is connected betweenband 38 affixed to jack 50 and a similar band 192 affixed to jack 82,and an upper linkage 94 is connected between bands 44 and 196 to jacks50and 82, respectively. The length of linkage 190 is determined by theoperation of a doubleacting, hydraulic thrust ram 198 having piston andcylinder elements constituting an integral part of the linkage in aconventional manner. Linkage 190 is afforded a multidirectional limitedangle swing with respect to bands 38 and 192 by universal couplings,such as is represented at junctures 200 and 202 connecting the linkageto the bands. Correspondingly, linkage 194 of section 26, and linkage204 and 2060f section 208 have as an integral part thereof double-actinghydraulic thrust rams 208, 210, and 212, respectively. and the juncturesof these linkages with bands affixed to the jacks operatively associatedtherewith are by way of universal couplings of the type hereinabooveindicated for linkage 190. As is now evident from the foregoing eachlinkage of the further linkage pairs of the side of the respectivedriver sections which is opposite to that appearing in FIG. 1, has as anintegral part thereof a double-acting, hydraulic thrust ram, and isconnected to jacks operatively associated therewith by way of universalcouplings at bands affixed to these jacks.

The generation of hydraulic power and a control of this power for aselective application thereof to the multiple jack and thrust ramarrangements comprising the motive means of the apparatus disclosedherein, are effectuated in the centrally situated power section 24. Eachside of the apparatus is served by a separate power and control unit ofsection 24, although a single unit of appropriate power generatingcapacity and control facilities may also have utility in the apparatus.In FIG. 1, a power unit 220, which appears as exemplary herein, is shownmaintained suspended between jacks 82 and 84 by four pivotal connectionsfrom vertical side supports 222 and 224 of the unit, to the previouslymentioned upper and lower bands affixed to the jacks. To the bed of aplatform 226, made integral with the side supports at the lower partsthereof, is secured a hydraulic oil supply tank 228, and mounted abovethe tank is a hydraulic pump and motor mechanism 230. lnterconnectingthe twelve jacks and eight thrust rams of the apparatus as disclosedherein, with oil supply 228 and motor driven pump mechanism 230, areconventional flexible hydraulic hoses and couplings, not shown, and asuitable hydraulic control system of a type well known in the relatedart which is exemplified by the control system disclosed in thepreviously identified patent to Fitzgerald. The various hydrauliccomponents of this system, including its multiplicity of bidirectionalvalve control boxes respectively connected to each of the jacks andthrust rams, are conveniently grouped and mounted under a controlconsole, displaying the operating handles of such valve boxes, which isattached to platform 226 of power section 24.

Advanced of the apparatus disclosed herein along a direct path followingthe longitudinal axis of the tunnel towards its face 240 is accomplishedby propulsion of its integral structure in a step-wise operation whereinthe jacks and thrust rams thereof are manipulated in the mannerhereinafter set forth. Starting with the apparatus fully extendedwherein the four thrust rams in each driver sections 26 and 28 areextended as shown by the condition of thrust rams 198 and 208 in linkage190 and 194, and all twelve jacks are extended so as to apply their pads68 firmly in contact with tunnel floor 16, and engage their controlspikes firmly in tunnel roof l8, wherefore all panels of canopy 10 aresupported in close proximity to the tunnel roof, the operation isinitiated with the pistons of the four jacks of back end section 22being retracted to take their conical spikes out of contact with tunnelroof 18 so as to withdraw panel away from the roof. Secondly, the fourthrust rams, including thrust rams 210 and 212, of the back end driversection 28 are operated to retract the four linkages thereof, includinglinkages 204 and 206, so as to advance section 22 toward all the otherstructures of the apparatus then firmly held by the extended jacksthereof. Thirdly, pistons of the four jacks of back end section 22 areextended to again firmly secure this section between the floor and roofof the tunnel. in this state of apparatus, intermediate panel 182 isrelaxed, and sags as shown in FIG. I. Fourthly, pistons of the fourjacksof power section 24 are retracted to free this section for displacement,wherefore panel 172 is withdrawn from the tunnel roof. Fifthly, the fourthrust rams of front end drive section 26 are operated to retract thefour linkages thereof, including linkages 190 and 194, concurrently withthe operation of the thrust rams of section 28 to extend the fourlinkages thereof, so as to move section 24 the distance of a linkagechange with respect to sections 20 and 22 which are then firmly fixedbetween the floor and roof of the tunnel. Sixthly, pistons of the fourjacks of power section 24 are extended to again firmly secure thissection between the floor and roof of the tunnel. in this state of theapparatus, intermediate panel is relaxed, and sags. Seventhly, pistonsof the four jacks of front end section 20 are retracted to free thissection for displacement wherefore panel I32 is withdrawn from thetunnel roof. Eightly, the four thrust rams of front end driver section26 are operated to extend their linkages so as to advance front endsection 20 with respect to sections 22 and 24 which are then firmlyfixed between the floor and roof of the tunnel. Thus, the entireapparatus has moved to displace canopy 10 ahead by the length of themotion given the thrust ram linkages. During any displacement occurringin the operation, two out of the three sections which comprise fourjacks are maintained secured between the floor and roof of the tunnel.

The apparatus herein is also susceptible of a wide range of othermotions. in one instance, all of the upright jacks at one side of thetunnel are maintained secured by engagement of their pads and spikeswith the floor and roof of the tunnel, and the step-wise operationpreviously set forth is applied only to the jacks at the other side ofthe tunnel. As a result, canopy 10 is displaced into a paralleogram-likeelement and its net width is reduced. In this manner, the width ofcanopy 10 can be reduced by approximately 30 percent to ad just tovariations in room width. Further, by alternate side operations of thisnature, canopy 10 can be moved in a direction to the right or left ofthe tunnel center line as desired. Moreover, a turn may be negotiated ifone of the rear jacks of the front end section is left engaged with thefloor and roof of the tunnel, and if that corner or any other corner ofthat section is locked to retain the section rectangular. Consequently,where the thrust rams on the side opposite the engaged jack is advanced,the section will turn about the engaged jack as a center, and a turn isthus started in a direction which may be perpetuated by handling thefollowing fourjack sections in the same manner as they reach the pointof turning. It should now be evident that a wide range of other motionsmay be practiced with the apparatus by appropriate management of theroof-engaging jacks and the thrust rams. In the event it is desired toset roof bolts through any portion of the panels composing canopy 10, apair of cross straps in such panel which are at right angles to eachother can be left out in any position where an opening is required. Theopening thus provided will permit bolt holes to be drilled and roofbolts to be installed.

In the further embodiment of the present invention illustrated in FIGS.7 and 8, each section of a multisection arrangement therein includes apair of caterpillar drive assemblies as integral parts thereof whichserve in place of the drive sections applicable to the embodiment of theinvention previously described. One side of a section comprising thisfurther embodiment appears in FIG. 7 where a caterpillar drive assembly300 is shown as having flexibly mounted to each of its extended ends asextensible upright jack mechanism comprising a double-acting hydraulicpiston device at the lower and upper ends thereof, respectively. Jackmechanism 302, which is adapted to function at one end of assembly 300,includes a tubular housing 304 wherein a cylindrical enclosure 306,affixed in the housing by conventional ring brackets. has operabletherein a lower piston device represented in FIG. 7 by its piston rod308, and an upper piston device represented in the figure by its pistonrod 310. An explanation in greater detail of this conventionalstructural arrangement of dual piston devices in a jack mechanism isavailable by reference to the disclosure of the previously identifiedpatent to Fitzgerald. Upper piston rod 310 supports by pivotalattachment thereto a relatively short cross beam 312 on which spikedposts, including post 314 visible in FIGv 7, are affixed at spacedpoints thereon, as was previously explained with respect to the firstembodiment of the present invention. Lower piston rod 310 has pivotallyconnected thereto a foot element or pad 316 which is adapted to rest ontunnel floor 16 when rod 310 is in its extended position. Integrallyformed on tubular housing 304 are a pair of spaced, circular flanges 318and 320 which are radially disposed a short distance below a centralcircumference of the housing. These flanges are enclosed within abearing box having the form of a relatively thick collar 322 looselyfitted on the tubular housing. More specifically, collar 322 has upperand lower central openings 324 and 326, respectively, through whichtubular housing 304 projects and is positioned where flanges 318 and 320reside contiguous to radially disposed internal surfaces of the collar.However, flanges 318 and 320 are free to move with respect to theinternal surfaces of collar 322 such that housing 304 is rotatable incollar openings 324 and 326.

Attachment of jack mechanism 302 to drive assembly 300 is facilitated bya spring-held pivotal connection 330 providing a flexible restraintwhich maintains the jack mechanism in an upright position a short distance from one end of the drive assembly. Spaced extension arms ofconnection 330, including arm 332 visible in FIG. 7. which are bolted tothe curved surface of collar 322, are further pivotally supported on adouble ear bracket, including car 334 visible in FIG. 7, of theconnection. In turn, the connection bracket is bolted to one end portionof a deck plate 336 of drive assembly 300. Constraining the aforesaidpivotal attachment as shown in FIG. 7, is a substantially arcuate, stiffleaf spring structure 338 affixed by retainer plates and bolts to collar322 between the aforesaid extension arms, and to deck plate 336 betweenthe bracket ears affixed to the deck. The other end of drive assembly300 is correspondingly equipped with a spring-held pivotal connection340 which is effective to flexibly restrain a jack mechanism 342 uprightat a short distance from the drive assembly. Moreover, as should beevident from the showing in FIG. 7,jack mechanism 342 and pivotalconnection 340 provided therefor; correspond in all particulars to theform and detail of jack mechanism 302 and its pivotal connection 330.

Drive assembly 300 is, in essence, a conventional hydraulically poweredcatcpillar motive means now well known in the art. Comprising thisassembly is a caterpillar chassis 350 wherein are operable cogged wheelswithin a roller belt, and to which is mounted deck 336. Further arrangedon deck 336 are an electric motor driven hydraulic pump 352, an oilreservoir 354, and a hydraulically driven motor 356 which impels theroller belt construction by way of a belt drive as shown in FIG. 7. Jackhousing 302 and the respective correspondingly constructed jack housingwhich is laterally spaced therefrom on the other side of tunnel 8, areflexibly interconnected by a spring beam structure of a form which morefully appears in the showing of FIG. 3 by lateral beam 58. Reference toFIG. 8 reveals a leaf spring component 360 of the laterallyinterconnecting beam which extends to jack mechanism 342 whereat thecomponent is affixed to a housing 362 of the jack mechanism by a boltedclamp device 364. Lower and upper piston rods 366 and 378, respectively,of the hydraulic piston enclosed in housing 362, are shown in FIG. 8 intheir extended condition where a cross beam 370, pivotally connected atthe extendedend of piston rod 368, thrusts spiked post 372, affixed toone end of the beam, and its counterpart spiked post, affixed to theother end of the beam, into roof 18 of the tunnel, and piston rod 366firmly plants a pad 374, pivotally connected to the extended endthereof, on floor 16 of the tunnel. Now believed to be evident from theforegoing is that beams 312 and 372, provide four spiked posts,including posts 314 and 372, for cooperation with the other generallyquadrangular arrangements of spike posts above pairs ofjack mechanisms,individually associated with a caterpillar drive unit, which arelaterally and longitudinally spaced from jack mechanisms 302 and 342, tosupport a canopy 380 which corresponds to all particulars to the formand details of construction and mounting ascribed to canopy 10 of theembodiment of the present invention first described. More particularly,canopy 380 includes longer panels, such as panel 382 shown in FIG. 7,which are individually supported and positioned by four jack mechanismsassociated with each of the several sections, and shorter intermediatepanels which are individually supported and positioned by fourjackmechanisms comprising the neighboringjacks of adjacent sections whichare normally spaced one from the other by the length of a shorter panel.

Maneuvering of any mobile portion of the FIGS. 7 and 8 embodimentrequires that its canopy 380 be lowered and its pads 316 and 374, beraised, as indicated in the showing of FIG. 7. The bearing collars forthe jack mechanisms, such as collar 322, provides angular verticalsupport so that a highly effective horizontal support is available inthe plane of the canopy which obtains protection from roof falls evenwhen the jack mechanisms are not engaged between the roof and floor ofthe tunnel, and stability of the overall apparatus as it travels andmaneuvers about the tunnel. Moreover, since no great vertical orhorizontal loads are normally carried by the caterpillar driveassemblies, the weight and strength of these assemblies can be greatlyreduced so as to provide a lighter, more maneuverable caterpillar andsupport structure of a reduced cross section, and thus provide a maximumclearance around men and machines in the tunnel. In case of a roof fallduring a moving operation, the tubular housings of the jack mechanismsare capable of moving with respect to the caterpillar drive assemblythereof by virtue of the mounting springs and the pivotal mountingassociated therewith connecting the bearing collar to the driveassembly. In case of an unusually heavy load, spiked posts and a pad ofa jack mechanism can be forced into engagement with the tunnels roof andfloor without passing any unduly heavy load to the drive assembly.Separate control of the hydraulic power to each section or part thereofis contemplated, although the requisite operator controls are normallysituated at a central point or points on the aperture. Selectiveoperation of the caterpillar drive assemblies with predetermined jackmechanisms being engaged with the tunnels roof and floor, permitscomplete steerability of the apparatus within the horizontal plane,including changing width of canopy 380, and turning it through angle oraround corners, by following procedures like those previously explainedin connection with the embodiment of FIGS. 1 to 6. In any case, theopposite side units, or complete sections of the apparatus are operablesingly, in pairs, all at one time, or in any other selected manner, toprovide the desired mobility.

Further reasonable variations and modifications are possible within thescope of the foregoing disclosure and the appended claims to theinvention.

I claim:

1. Manipulated apparatus for protection against the hazards of rooffalls in underground tunnels which is operatively responsive to aselectively controlled power means comprising a flexible shieldingmeans, and

a mobile mechanism having operable therein a plurality of reciprocableand pivotable devices, and means, activatable by said controlled powermeans, to propel said mechanism with respect to said tunnel, saiddevices including elements, activatable by said controlled power means,to displace components affixed in a predetermined spatial arrangementthereon between first and second dispositions with respect to saidtunnel, said components having said shielding means depend therefrom andare effective by activation of said elements which displaces saidcomponents from said first to said second disposition thereof tomaintain said shielding means in close proximity to a roof of saidtunnel, and by activation of said elements which displaces saidcomponents from said second to said first disposition thereof tomaintain said shielding means free from engagement with said roof, andsaid propelling means being adapted for operation upon activationthereof when said components are in said first disposition thereof.

2. The apparatus of claim 1, wherein said plurality of devices includesjacks having reciprocable and rotatable pistons, and cross beamspivotally mounted on said pistons and displaceable therewith, and saidcomponents comprise posts surmounted by pointed parts whereby said postsserve to facilitate nonrigid connections between said shielding meansand said beams, and said pointed parts serve to maintain said shieldingmeans in close proximity to said tunnel roof by engagement with saidroof.

3. The apparatus of claim 2 wherein said nonrigid connections includesubstantially oval rings having a relatively wide end opening whichfacilitates depositing said rings upon said posts and fixing saidshielding means to said rings, and a relatively narrow end opening whichfacilitates securing said ring to said post.

4. The apparatus of claim 2 wherein said mobile mechanism comprises aplurality of sections, and said plurality of devices includes as a partthereof arrangements of jacks associated with said sections, each saidjack having at least one reciprocable and rotatable piston operabletherein, and said shielding means comprises a plurality of panels ofwhich each panel is operatively associated with a predetermined one ofsaid plurality of sections, whereby said nonrigid connections maintaineach said panel over said section associated therewith. 7

5. The apparatus of claim 4, wherein each panel is generallyquadrangular in shape, and includes shape defining cables extendingalong the respective edges of said panel, flexible webbing strapssupported on said cables by retaining said cables in loops of saidstraps formed at the extremities thereof, said straps being in terlacedin a generally loose mesh pattern, and said nonrigid connectionsincluding coupling rings which engage said posts of said components andhave end portions of said cables secured thereto.

6. The apparatus of claim 5 wherein predetermined opposite edges ofalternate panels of said shielding means have a curved shape, andalternate panels between said predetermined edges have edges opposite tosaid predetermined edges whereby a generally uniform close spacingbetween said panels is achieved.

7. The apparatus of claim I wherein said mobile mechanism comprises aplurality of displaceable sections including a front end section, a backend section, a central section, and intermediate sectionsinterconnecting said central section with said front and back endsections, each of said sections having as parts thereof first and secondside units, each said side unit of said end and central being part ofsaid activatable elements including a pair of spaced jacks, a pluralityof support members extending between said jacks and pivotally connectedthereto, corresponding jacks of said first and second units of each saidend and central sections being interconnected by a flexible beam,whereby said support members and said flexible beam maintain said jacksin a generally upright disposition, each said side unit of saidintermediate sections being part of said means to propel including apair of doubleacting extensible thrust rams which are operablyresponsive to activation thereof by said controlled power means, saidthrust rams of each said pair being spaced where they are separatelyoperable by way of universal connections between a different one of saidjacks of said central section and a jack closest thereto in one of saidend section side units, whereby said thrust ram when activated functionsalternately to draw said jacks connected thereto a predetermineddistance toward one another, and to spread said jacks connected theretosaid predetermined distance away from each other, said central sectionhaving in each side unit, as an integral part thereof, a platformstructure whereon said selectively controlled power means is disposedfor operation, and means attached to upper extensible parts of saidjacks of said apparatus whereon said components are spatially arrangedand whereby said shielding means is maintained dependent therefrom so asto extend over all said sections of said apparatus.

8. The apparatus of claim 1 wherein said mobile mechanism comprises aplurality of displaceable sections, each said section having first andsecond side units, each said side unit comprising first and secondportions constituting parts of said activatable elements and said meansto propel, respectively, said first portion including a pair of jackstructures, each said structure having an upper and a lowerdouble-acting extensible means and a cylindrical housing containing saidextensible means such that an extension of said upper extensible meansis displaceable through an upper opening of said housing and anextension of said lower extensible means is displaceable through a loweropening of said housing, said extensible means being activatable inresponse to said selectively controlled power means to alternatelyproject and retract said displaceable extensions thereof with respect tosaid housing and the openings therein, spaced radial extensions madeintegral with said housing at spaced outer surfaces thereof,

a bearing support collar in which said radial extensions aresubstantially enclosed and in sliding contact with internal surfaces ofsaid collar whereby said housing with said extensible means therein arerotatable with respect to said collar, and said second portion includinga caterpillar'tractor means assembly having means affixed to a deck ofsaid tractor which constitutes part of said selectively controlled powermeans, and a drive to said tractor means in response to activationthereof by said selectively controlled power means, separate pivotalmeans attached to said tractor deck .at opposite ends thereof, eachpivotal means having a segment thereof outwardly disposed beyond the endof said tractor deck related thereto, each said segment having affixedthereto one of said jack structures by attachment to said bearingsupport collar provided therefor, a substantially curved leaf springassociated with each pivotal means, such that each said jack structureis further attached to said deck by said leaf spring, corresponding jackstructures of said first and second units of each said sections beinginterconnected by a flexible beam having extended ends thereof affixedto said cylindrical housings of said interconnected jack structures,whereby said pivotal means and said leaf spring associated therewith,and said flexible beam maintain said jacks in a generally uprightdisposition, a foot pad means pivotally connected to the end of saidextension of each of said lower extensible means, and means pivotallyconnected to the end of said extension of said upper extensible meanswhereon said components are spatially arranged and whereby saidshielding means is maintained dependent therefrom so as to extend overall said sections of said apparatus.

1. Manipulated apparatus for protection against the hazards of rooffalls in underground tunnels which is operatively responsive to aselectively controlled power means comprising a flexible shieldingmeans, and a mobile mechanism having operable therein a plurality ofreciprocable and pivotable devices, and means, activatable by saidcontrolled power means, to propel said mechanism with respect to saidtunnel, said devices including elements, activatable by said controlledpower means, to displace components affixed in a predetermined spatialarrangement thereon bEtween first and second dispositions with respectto said tunnel, said components having said shielding means dependtherefrom and are effective by activation of said elements whichdisplaces said components from said first to said second dispositionthereof to maintain said shielding means in close proximity to a roof ofsaid tunnel, and by activation of said elements which displaces saidcomponents from said second to said first disposition thereof tomaintain said shielding means free from engagement with said roof, andsaid propelling means being adapted for operation upon activationthereof when said components are in said first disposition thereof. 2.The apparatus of claim 1, wherein said plurality of devices includesjacks having reciprocable and rotatable pistons, and cross beamspivotally mounted on said pistons and displaceable therewith, and saidcomponents comprise posts surmounted by pointed parts whereby said postsserve to facilitate nonrigid connections between said shielding meansand said beams, and said pointed parts serve to maintain said shieldingmeans in close proximity to said tunnel roof by engagement with saidroof.
 3. The apparatus of claim 2 wherein said nonrigid connectionsinclude substantially oval rings having a relatively wide end openingwhich facilitates depositing said rings upon said posts and fixing saidshielding means to said rings, and a relatively narrow end opening whichfacilitates securing said ring to said post.
 4. The apparatus of claim 2wherein said mobile mechanism comprises a plurality of sections, andsaid plurality of devices includes as a part thereof arrangements ofjacks associated with said sections, each said jack having at least onereciprocable and rotatable piston operable therein, and said shieldingmeans comprises a plurality of panels of which each panel is operativelyassociated with a predetermined one of said plurality of sections,whereby said nonrigid connections maintain each said panel over saidsection associated therewith.
 5. The apparatus of claim 4, wherein eachpanel is generally quadrangular in shape, and includes shape definingcables extending along the respective edges of said panel, flexiblewebbing straps supported on said cables by retaining said cables inloops of said straps formed at the extremities thereof, said strapsbeing interlaced in a generally loose mesh pattern, and said nonrigidconnections including coupling rings which engage said posts of saidcomponents and have end portions of said cables secured thereto.
 6. Theapparatus of claim 5 wherein predetermined opposite edges of alternatepanels of said shielding means have a curved shape, and alternate panelsbetween said predetermined edges have edges opposite to saidpredetermined edges whereby a generally uniform close spacing betweensaid panels is achieved.
 7. The apparatus of claim 1 wherein said mobilemechanism comprises a plurality of displaceable sections including afront end section, a back end section, a central section, andintermediate sections interconnecting said central section with saidfront and back end sections, each of said sections having as partsthereof first and second side units, each said side unit of said end andcentral being part of said activatable elements including a pair ofspaced jacks, a plurality of support members extending between saidjacks and pivotally connected thereto, corresponding jacks of said firstand second units of each said end and central sections beinginterconnected by a flexible beam, whereby said support members and saidflexible beam maintain said jacks in a generally upright disposition,each said side unit of said intermediate sections being part of saidmeans to propel including a pair of double-acting extensible thrust ramswhich are operably responsive to activation thereof by said controlledpower means, said thrust rams of each said pair being spaced where theyare separately operable by way of universal connections between adifferent one of said jacks Of said central section and a jack closestthereto in one of said end section side units, whereby said thrust ramwhen activated functions alternately to draw said jacks connectedthereto a predetermined distance toward one another, and to spread saidjacks connected thereto said predetermined distance away from eachother, said central section having in each side unit, as an integralpart thereof, a platform structure whereon said selectively controlledpower means is disposed for operation, and means attached to upperextensible parts of said jacks of said apparatus whereon said componentsare spatially arranged and whereby said shielding means is maintaineddependent therefrom so as to extend over all said sections of saidapparatus.
 8. The apparatus of claim 1 wherein said mobile mechanismcomprises a plurality of displaceable sections, each said section havingfirst and second side units, each said side unit comprising first andsecond portions constituting parts of said activatable elements and saidmeans to propel, respectively, said first portion including a pair ofjack structures, each said structure having an upper and a lowerdouble-acting extensible means and a cylindrical housing containing saidextensible means such that an extension of said upper extensible meansis displaceable through an upper opening of said housing and anextension of said lower extensible means is displaceable through a loweropening of said housing, said extensible means being activatable inresponse to said selectively controlled power means to alternatelyproject and retract said displaceable extensions thereof with respect tosaid housing and the openings therein, spaced radial extensions madeintegral with said housing at spaced outer surfaces thereof, a bearingsupport collar in which said radial extensions are substantiallyenclosed and in sliding contact with internal surfaces of said collarwhereby said housing with said extensible means therein are rotatablewith respect to said collar, and said second portion including acaterpillar tractor means assembly having means affixed to a deck ofsaid tractor which constitutes part of said selectively controlled powermeans, and a drive to said tractor means in response to activationthereof by said selectively controlled power means, separate pivotalmeans attached to said tractor deck at opposite ends thereof, eachpivotal means having a segment thereof outwardly disposed beyond the endof said tractor deck related thereto, each said segment having affixedthereto one of said jack structures by attachment to said bearingsupport collar provided therefor, a substantially curved leaf springassociated with each pivotal means, such that each said jack structureis further attached to said deck by said leaf spring, corresponding jackstructures of said first and second units of each said sections beinginterconnected by a flexible beam having extended ends thereof affixedto said cylindrical housings of said interconnected jack structures,whereby said pivotal means and said leaf spring associated therewith,and said flexible beam maintain said jacks in a generally uprightdisposition, a foot pad means pivotally connected to the end of saidextension of each of said lower extensible means, and means pivotallyconnected to the end of said extension of said upper extensible meanswhereon said components are spatially arranged and whereby saidshielding means is maintained dependent therefrom so as to extend overall said sections of said apparatus.